Low profile resonant plow

ABSTRACT

A sonically-driven resonator of a resonant plow or trenching tool is formed so that at least its major dimension extends in a plane substantially parallel to the surface of the earth formation being plowed and extends substantially along the direction of travel so as to reduce the vertical dimension thereof and any interference with overhead structures.

United States Patent [72] Inventor Howard L. Slutto Refel'gncgs Cit d 2A I N 2}: UNITED STATES PATENTS 1 g fi, 1968 3,387,668 6/1968 Mathers172/719 Patented 1 Lamb [73] Assignee Shell 01 Company 3,231,025 l/1966Bodine 172/40 New York N Y 3,339,641 9/1967 Carter 172/40 3,398,7988/1968 Shelton 172/1 3,461,970 8/1969 Bodine 172/1 3,461,969 8/1969Bodine, Jr. 172/1 PrimaryExaminer-Robert E. Pulfrey 54 w PR 580"Assistant Examiner-Clifford D. Crowder l 3 gg no. Low Attorneys-J. H.McCarthy and Freling E. Baker [52] US. Cl. 172/40,

299/14, 173/49, 37/ 193, 172/773, 37/98 ABSTRACT: A sonically-drivenresonator of a resonant plow [51] Int. Cl. A011: /00, or trenching toolis formed so that at least its major dimension 1321537120 extends in aplane substantially parallel to the surface of the [50] iieldofselrch172/1, 699, earth formation being plowed and extends substantially along763, 88, 776, 719, 37/( VD), 193, 195; the direction of travel so as toreduce the vertical dimension til/72.5, 72.6; 173/49; 299/14, 37 thereofand any interference with overhead structures.

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' nm 1 OF 2 FIG. I

INVENTORI H. SHATTO BYI HIS ATTORINEY LOW PROFILE RESONANT nowBACKGROUND OF THE INVENTION 1. Field of the Invention Thepresentinvention relates to the plowing of trenches and pertains moreparticularly, to the application of sonic energy to a plowing ortrenching tool for forming trenches in which to lay cables. pipes andsimilar structures.

2. Description of the Prior Art The potential benefits of applying sonicenergy to cable plows and other earth working tools have been known forsome time. These proposed prior art devices, however, utilize anenormous resonant member or bar to transmit the energy from theoscillator to the plow blade. A major disadvantage of these prior artdevices is that the resonator bar becomes too large and bulky whendesigned for deep trenching. This is because the nodes (points ofminimum amplitude of velocity and motion) of the bar must be'positionedabove the surface of the ground for most efficient operation. Theresonator, an elongated rectangular bar in these prior devices, willvibrate transversely as a free-free bar with two nodes or points ofminimum vibration. These nodes will be located at points aboutone-quarter of the length of the bar from each end. Therefore, to keepthe lower node of such a resonant bar above the ground for a three footdeep trench, a bar of uniform cross section must be greater than 4 times3 or greater than l2 in length. Such a resonant bar would extend greaterthan 9 vertically into the air when in the operative position or greaterthan 12 when in the inoperative position. Such an apparatus is bulky anddifficult to handle and limited in its use because of its interferencewith overhanging structures such as tree branches, buildings, and powerlines. Another major difficulty with such prior art devices is that thenecessary positioning'of the sonic vibration generator on the resonantbar is such that it cannot be readily driven from the power takeoff of atowing vehicle. The sonic vibration generator must be placed at or nearan antinode for best results. These antinodes appear at the ends and atthe center of the bar. Thus, the sonic vibration generator must beconnected to the bar at its center or at its upper end.

Summary of the Invention It is the primary object of the presentinvention to overcome the above objections of the prior art by providinga resonant so'nic trencher that is compact and easy to manipulate.

A further object of the present invention is to provide a resonant sonictrencher formed such that the sonic generator may be positioned thereonfor direct drive from the powertakeoff of a towing vehicle.

In accordance with the invention the resonator bar of a resonant sonicplow is formed such that the axis of a major portion thereof extendssubstantially along the direction of travel and in a substantiallyhorizontal plane in order to form an apparatus having a very lowprofile. Other significant aspects of the invention include forming theresonator bar for maximum 0. or sharpness of resonance, per pound ofmaterial.

Brief Description of the Drawing ment of the present invention;

. FIG. 6 is a cross-sectional view taken along line 6-6 of the apparatusof FIG. I

FIG. 7 is a schematic elevational view of still another embodiment ofthe present invention;

embodi- FIG 8 IS a schematic elevational view of a further embodiment ofthe apparatus of the present invention;

FIG 9 is a schematic elevational view of a still further embodiment ofthe present invention.

In order to facilitate the comprehension of the principles involved inthe present invention, an analogy may be drawn between the acousticallyvibrating circuit and an equivalent electrical circuit. Such an analogyiswell known to those skilled in the art and is described in Chapter 2of "Sonics" by Hueter and Bolt, published in 1955 by John Wiley andSons, In this analogy, mechanicalforce F is equated to electricalvoltage E; velocity of vibration u is equated with electrical currenti,mechanical compliance Cm is equated with electrical capacitanceCennass M is equated with electrical inductance -L;mechanic'alresistance (friction) Rm is equated with electrical resistance R;andmechanical impedance Zm is equated with electrical impedance Ze.Thus, itcan be shown that if a member is elastically vibrated by means of anacoustical sinusoidal force F0 sin an, to being equal to 21r times thefrequency of vibration, that In such a system, the peak resonantcondition will exist where wM is equal to l/mCm, and the effectivemechanical impedance Zm is reduced to its minimum value which is simplythe mechanical resistance, and the reactive impedance components 10M andI/wCM will cancel each other out. At resonance, the velocity ofvibration u will be at the maximum effective power factor of unity, andenergy is most effectively delivered to a load to which the system maybe coupled.

Description of Preferred Embodiments In FIGS. 1 and 2 are illustrated apreferred embodiment of the invention which comprises a self-propelledtransport vehicle 11 having prime mover means 12 coupled throughtransmission means in a conventional manner to traction wheels 13. Inthis embodiment the resonator assembly comprises a resonant member 14 inthe shape of an inverted U which is pivotally supported at its nodalpoints by pins 15 and 16 to link members 17 and 18 which are connectedto shafts 19 and 20 which are connected in a conventional manner torotatable means on vehicle 11 for raising and lowering the resonatorassembly. The U-shaped for the resonator bar approaches that of a tuningfork but may be constructed so as to have two vibrational nodes as in astraight rectangular rather than one asin the tuning fork. Thisconstruction provides two places at which the bar may be connected tosupporting and manipulating framework or mechanism. Actually, the truenodal points for a bar like that illustrated has been found to appearsomewhere above the bar. However, for the purposes of this illustration,points designated on the bar will be selected for the attachment ofsupporting structure. A sonic vibration generator 21 is connected in anysuitable manner to the forward leg of the resonator bar 14 and is drivenby means of a telescoping cardon shaft 22 from power-takeoff shaft 23 ofthe prime mover means 12 of vehicle 11. A trenching tool 24, whichlspreferably constructed of a good grade of tool steel and having a point25, is coupled to the trailing leg of the resonator bar 14. The resonantmember 14 may be a laminated structure constructed of a number ofU-shaped plates l4a,14b,l4c having tapered progressively shorter legs.The plates may be connected together by:press-fitting bolts or rivets inholes arranged along the centerline of the plate. This is the area of Inthe modification illustrated in FIGS. 3 and 4, the resonant member 26 isshown as being formed in substantially the same U-shaped configurationas that of FIG. 1, but with a different cross-sectional configuration.The substantially H or I crossi sectional configuration of thismodification permits the attainment of an even higher Q for a givenpound of material (generally steel) in the resonator. This is becausethe stress in the bar varies from about zero at its center to a maximumat its outer surfaces when the bar vibrates in its lateral mode. Inother words, the outer grains are highly stressed, while the centergrains receive very little stress. Thus, only a relatively thin web 26ais needed to connect the flanges 26c and 26d together. This constructionplaces the maximum amount of material in the area of maximum stress. Theresonant member 26 is pivotally connected at the nodes by means of pairsof links 27 and 28 to a raising and lowering mechanism on a transportvehicle such as that shown in FIG. 1. A sonic vibration generator 29 isrigidly connected in any suitable manner such as by bolting or clampingto the forward leg 26a of the resonant member 26. The sonic vibrationgenerator 29 is schematically illustrated as a single bar orbiting rotortype, buy may be any type as discussed above. The sonic generator isdriven by means of drive shaft 30 from a powertakeoff shaft such as thatof the prime movervehicle. It is also apparent that the sonic vibrationgenerator may be coupled to the resonant member at other points totransfer the energy thereto. For example, the sonic generator may becoupled at the center of the midsection, or at the lower end of thetrailing leg 26b.A cutting or trenching tool 31 is attached in anysuitable manner such as by riveting or bolting between plates 32 to therear or trailing leg 26b of the resonant member 26.

A further embodiment of the present invention is illustrated in FIGS.and 6. In this embodiment the resonant member 33 has a boxlikecross-sectional configuration with thick upper and lower walls andrelatively thin sidewalls. This construction obtains relatively the samebenefits as the embodiment of FIGS. 3 and 4. In this embodiment a pairof thick plates 33c and 33d are connected together by a pair of thinplates 33s and 33f. The resonant member is supported at its nodes from atransport vehicle in any suitable manner, as by pivoting links 34 and35. A sonic vibration generator 36 is connected in any suitable manner,as by clamping or bolting to the trailing leg 33b of the resonantmember. The sonic vibration generator is illustrated as being fluiddriven with fluid supply and exhaust conduits 37 and 38, respectively. Acounterweight 39 is attached to the forward leg of the resonant memberto counterbalance the system. A cutting or trenching tool 40 isconnected to the rear leg 33b of the resonant member. This arrangementprovides a more direct drive of the trenching tool from the sonicvibration generator with the resonator bar storing energy to smooth outthe pulses.

The modification of FIG. 7 provides a rugged and economical arrangementwhich maintains a low profile where the linear or horizontal space isnot a problem. In this embodiment the resonant member 41 is in the formof elongated rectangular bar having its axis extending along thepredetermined direction of travel and substantially parallel to thesurface of the earth formation being cut. A cutting or trenching tool 42extends downward from the resonant member at a point near one node forengagement with the earth formation. The trenching tool is formed ormounted on the resonant member such that its point travels in an areabout the node. The point of the trenching tool may be positioned suchthat it reaches a point directly below the node at its forwardmost pointof travel for most ordinary soils. For chipping and breaking layers ofrock or pavement, it may be desirable that this forwardmost point oftravel be forward of the point directly below the node so that the pointtravels slightly upward toward the end of its forward travel. A sonicvibration generator 43 is connected to the resonant member atsubstantially at a point about halfway between the nodes. It is also tobe understood that the generator may also be connected to the resonantmember at either end. The resonant member 4] is pivotally supported atits nodes by suitable means such as link means 44 connected to asuitable transport vehicle. The wave patterns 45 graphically Illustratethe relative amplitude oi vibration of various points along the resonantmember. As illustrated, the nodes normally go through very minoramplitudes of vibration.

In FIG. 8 is illustrated a modification wherein the resonant member 46is curved so as to retain two seminodal areas and having its majordimension extending along the direction of travel and substantiallyparallel to the surface of the earth formation. One end of the member iscurved downward to present a portion thereof for engagement with theearth formation to form a cutting or trenching tool. A sonic vibrationgenerator 47 is mounted on the forward end of the resonant member totransmit sonic vibrations thereto. The apparatus may be supported from asuitable transport vehicle by like means 48 pivotally connected to thenodal areas of the resonant member.

A further embodiment of the invention is illustrated in FIG. 9 in whichthe resonant member 49 has its major dimension extending substantiallyalong the direction of travel and its forward end extending downward onwhich is formed or connected a cutting or trenching tool for engagementwith an earth formation. A sonic vibration generator 50 is connected tothe other end of the resonator bar to transmit sonic vibrations thereto.The apparatus is supported from a suitable transport vehicle by linkmeans 51 connected to the nodal points of the resonant member.

Various modifications may be made in the construction and arrangement ofthe apparatus without departing from the scope of the invention asdefined in the appended claims.

lclaim:

1. In a sonic earth plow mounted on a carrier vehicle for movementtherewith along a predetermined direction of travel:

an elastic resonant member comprising an elongated midsection, saidresonant member having its midsection extending along said direction oftravel;

a pair of tapered legs extending downward from said midsection to form asubstantially U-shaped configuration; earth cutting means connected tothe end of one of said legs; and

a vibration generator connected to said resonant member on one of itssaid legs, whereby vibrations created by said vibration generator aretransmitted to said earth cutting means through said elastic resonantmember to thereby vibrate said earth cutting means in a planecoextensive with said direction of travel.

2. The apparatus of claim 1 wherein:

said cutting means is connected to the end of one of said legs; and

said vibration generator is connected to the other leg of said resonantmember.

3. The apparatus of claim 1 wherein said resonant member comprises:

a plurality of relatively thin members connected together to form alaminated structure.

1. In a sonic earth plow mounted on a carrier vehicle for movementtherewith along a predetermined direction of travel: an elastic resonantmember comprising an elongated midsection, said resonant member havingits midsection extending along said direction of travel; a pair oftapered legs extending downward from said midsection to form asubstantially U-shaped configuration; earth cutting means connected tothe end of one of said legs; and a vibration generator connected to saidresonant member on one of its said legs, whereby vibrations created bysaid vibration generator are transmitted to said earth cuttIng meansthrough said elastic resonant member to thereby vibrate said earthcutting means in a plane coextensive with said direction of travel. 2.The apparatus of claim 1 wherein: said cutting means is connected to theend of one of said legs; and said vibration generator is connected tothe other leg of said resonant member.
 3. The apparatus of claim 1wherein said resonant member comprises: a plurality of relatively thinmembers connected together to form a laminated structure.